A problem long recognized to exist with the operation of combine harvesters is that of the airborne dust resulting from gathering the harvested crop and conveying the crop through the feederhouse toward the threshing system provided following the feederhouse. In particular, the flow of material through the feederhouse is met with an opposite airflow, caused by the backpressure of the cleaning fan and/or other processing elements which produces a large plume of dust exiting the feederhouse. This plume of dust obstructs the operator's view of the gathering head, which is desirable in order for the operator to discern any difficulties and make any necessary adjustments.
Over the years, various schemes have been attempted for alleviating the dust/visibility problem. Specifically, U.S. Pat. Nos. 3,094,829; 3,187,491; 3,213,598; 5,322,472 and 6,036,500 each disclose dust collection devices comprising collection chambers mounted at various locations along associated feederhouses, the chambers containing a fan and being in communication with the inside of the feederhouse so that the fan draws dust into the housing and expels it through discharge chutes arranged in various ways for discharging the dust at various locations including on the ground alongside the feederhouse, (first three and last of the cited patents) into the chaffer sieve or straw chopper (the fourth cited patent). Another type of device is disclosed in U.S. Pat. Nos. 3,669,224 and 6,979,261, which each include an air deflector located between the discharge end of the feederhouse, the deflector, in case of the first cited patent, being located so as to prevent an air stream generated by an undershot threshing cylinder from creating turbulence at the discharge end of the feederhouse by deflecting the air back to an underside of the threshing cylinder, with the deflector, in the case of the second-cited patent, being located so as to prevent backflow from a beater and to channel air exiting the feederhouse along a path passing over the deflector and into the processing chamber of an axial threshing rotor.
The prior art devices utilizing fans have the disadvantage that they are auxiliary or add-on devices which are not very cost effective, and the fan arrangements of some of the devices draw air in a direction opposite to that of crop flow and/or are prone to plugging. While the prior art devices utilizing air deflectors are cost effective, they are not entirely satisfactory since they interfere with crop flow and in instances where the crop processor elements are running slow, the air flow created is not sufficient to draw off the dust.